30" spaced rafters in old house

Hello,

I have taken out the ceiling in the kitchen I am vaulting the ceiling in an old house. The roof already sags, I have put in 4 sky lights. The rafters are 30" on center 2 x 6 spanning about 15' from wall to peak. There are no collar ties. I am not trying to make the roof flat but for structural purposes should I add rafters and or collar ties for support? I live in Cleveland and well...we get heavy snow at times. Thank you for any help.

A friend of yours is doing this to YOUR house? You should probably have a discussion immediately with your friend as to their level of understanding of framing and structural support. For your information, collar ties are used to equalize uplift pressure on the opposite sides of the roof during high winds. Collar ties are not intended to resist outward thrust of rafters. To resist outward thrust, you need floor joists or you need to install a ridge beam and connect the rafters using special brackets. In any case, converting a structure from rafters with floor joists to a cathedral ceiling requires careful design, and structural modifications to the building.

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To Dan, Thanks for the post. This is a long story, but in short a friend buys and sells houses....had a great contractor doing the rehabs for them, they had a falling out and he now thinks he can manage on his own and save money. I walked in there and my eyes blew up (I built homes with my Dad growing up). The reason I posted was that he said he had an architect draw up plans and make changes that needed to be made after the house was gutted and re-configured (stairway was changed, went from a 3 to a 2 bedroom, added a bath, vaulted the ceiling etc etc.). Architect made no mention of having to correct the structure of the ceiling in his plans submitted to the city. I appreciate the input and please stay tuned for the pictures...could be entertaining!

To Dan, Thanks for the post. This is a long story, but in short a friend buys and sells houses....had a great contractor doing the rehabs for them, they had a falling out and he now thinks he can manage on his own and save money. I walked in there and my eyes blew up (I built homes with my Dad growing up). The reason I posted was that he said he had an architect draw up plans and make changes that needed to be made after the house was gutted and re-configured (stairway was changed, went from a 3 to a 2 bedroom, added a bath, vaulted the ceiling etc etc.). Architect made no mention of having to correct the structure of the ceiling in his plans submitted to the city. I appreciate the input and please stay tuned for the pictures...could be entertaining!

"Could be entertaining" is an understatement. with 30" oc rafters, what did they use for sheathing? 5/4 oak might be strong enough, anyway, good luck and looking forward to updates.

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